After N.A.D, other than an overlap with module metalwork, screws were metric thread with M3.5 retained front panels, M3 retained module front panels, and M2 retained amplifiers in motherboards.

Other than paint colour, most N.A.D modules can be identified by their module number having an additional (3) in front. i.e. 1073 became 31073

2. How can I make a mic preamplifier out of a 1272/3415/etc., line amplifier?

First you need to find the hardware. You need the mating connector, a metal case or front panel to mount the module in and a good 24v @ 1 amp dc power supply. The later can be bought provided it has low noise and ripple figures or you can build one with a suitable 24v secondary transformer, bridge rectifier, 4,700uF 50v capacitor and a 7824 regular with 220nF (I/P) and 470nF (O/P) capacitors to 0v to keep it all stable. Make sure you ground the power supply metalwork, the 0v of the output, and the casework of the module (usually the last pin on the connector).

You will need a rotary switch for the input gain and a 10Kohm audio taper (Log law) potentiometer for the output level control. Generally you need a two pole switch connected to the front and rear gain boost connections. The gain should be increased incrementally in either 5dB or 10dB steps and the front and rear gains raised together (or in sequence) such that the gain is spread across the whole module and not just dumped on the preamplifier. As for values of resistance per gain point, these are listed below in FAQ #3. NB. Both these amplifiers have around 36dB basic gain so you only need another 34dB to achieve 70dB gain.

The 1272 and like modules can be rack mounted via the four screws that retain the front panel. There is minimal strength in the front panel of the 3415 so I suggest screwing the extruded aluminium side cover to a rack bottom panel and drawing the module out like a drawer. Use countersink headed screws on the inside as there is minimal clearance.

3. What value resistance should I used to get “n”dB gain increase in a 1272/3415?

dB increase in Gain

B183/283 Front

B183/283 Rear *

3415 Front

3415/6 Rear

1

2200

6800

3600

4700

2

1000

3300

1600

2400

3

680

2200

1100

1500

4

470

1500

750

1100

5

360

1100

560

820

6

270

910

430

620

7

220

680

360

510

8

180

560

300

430

9

150

470

240

360

10

130

390

200

300

11

110

330

180

240

12

91

300

150

220

13

82

240

130

180

14

68

220

110

160

15

62

200

91

130

16

51

160

2

120

17

47

150

75

100

18

39

130

62

91

19

36

110

56

82

20

30

100

47

75

21

27

43

62

22

24

39

56

23

22

33

47

24

18

30

25

16

27

26

15

24

27

13

20

28

11

29

10

30

9.1

* The 1272 requires an external 100uF capacitor to decouple the rear gain boost resistor.
In all cases check that the low frequency response is not affected at high gains and increase the value of the internal decoupling capacitor if this is the case.

PS I am frequently asked how to convert a Neve 1271 line amplifier to a Neve 1272 line amplifier. As this involves internal wiring changes this can prove tedious to detail in full, I am attaching the internal wiring info for both modules so you can figure it yourselves!

You can see how the 1271 circuit diagram was drawn from a copy of the 1272 circuit with the extra components scratched out and more detail added to the BA183AV.

4. My module has stopped working! Where should I look for the fault?

This depends on the nature of the fault. If the module is working, just, but sounds terrible, the nature of the sound can help identify the fault. If it sounds really “thin” with only high frequency passing, it may be a poor seating of the module and the transformer coupling is one legged, causing the return path to be capacitively coupled. Re-seat or clean the connectors. Lack of bass frequencies along with distortion is usually down to electrolytic capacitors in series with the audio path. On a BA283, for instance, the two capacitors next to the heat sink.

A total absence of signal may be a shorted capacitor on the secondary of the input transformers, a burnt out/open circuit resistor in the positive power path, or a transistor with a blown junction. Most of these points can be checked with a digital multimeter.

The most common quarter turn fastener used to hold rear panels, etc., on are made by Dzus. These are very common as they are also used on aircraft engine covers, etc. Undernath the faders and the lower front panels, the fasteners are made by Oddie Fasteners (now Savigny Oddie Ltd). These are unusual as a quarter turn releases the panel and, to replace the panel, the fastener is turned back to its original position and then the panel banged into position with the side of your fist… a hammer is never needed!

The fasteners in the top wood are made by Camlock and the shell is recessed into the wood. These are also quarter turn and one should always make a note… even a marker pen under the panel… as to which console section the wood came from and which edge was the front!

6. Where can I obtain spare parts for my vintage Neve console or module?

I have created a long list of Neve sparts suppliers on the Neve Secrets Forum. You will need to log in to access this forum